diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
index 877fff2..2e6c4b2 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
@@ -87,7 +87,7 @@
 
             if (p.mNumOfCharGroup == Position.NOT_READ_GROUPCOUNT) {
                 p.mNumOfCharGroup = BinaryDictInputOutput.readCharGroupCount(buffer);
-                p.mAddress += BinaryDictInputOutput.getGroupCountSize(p.mNumOfCharGroup);
+                p.mAddress += getGroupCountSize(p.mNumOfCharGroup);
                 p.mPosition = 0;
             }
             if (p.mNumOfCharGroup == 0) {
@@ -101,9 +101,9 @@
             }
             p.mPosition++;
 
-            final boolean isMovedGroup = BinaryDictInputOutput.isMovedGroup(info.mFlags,
+            final boolean isMovedGroup = isMovedGroup(info.mFlags,
                     formatOptions);
-            final boolean isDeletedGroup = BinaryDictInputOutput.isDeletedGroup(info.mFlags,
+            final boolean isDeletedGroup = isDeletedGroup(info.mFlags,
                     formatOptions);
             if (!isMovedGroup && !isDeletedGroup
                     && info.mFrequency != FusionDictionary.CharGroup.NOT_A_TERMINAL) {// found word
@@ -130,7 +130,7 @@
                 p.mAddress = buffer.position();
             }
 
-            if (!isMovedGroup && BinaryDictInputOutput.hasChildrenAddress(info.mChildrenAddress)) {
+            if (!isMovedGroup && hasChildrenAddress(info.mChildrenAddress)) {
                 Position childrenPos = new Position(info.mChildrenAddress + headerSize, index);
                 stack.push(childrenPos);
             }
@@ -187,12 +187,10 @@
                     final int charGroupPos = buffer.position();
                     final CharGroupInfo currentInfo = BinaryDictInputOutput.readCharGroup(buffer,
                             buffer.position(), header.mFormatOptions);
-                    final boolean isMovedGroup =
-                            BinaryDictInputOutput.isMovedGroup(currentInfo.mFlags,
-                                    header.mFormatOptions);
-                    final boolean isDeletedGroup =
-                            BinaryDictInputOutput.isDeletedGroup(currentInfo.mFlags,
-                                    header.mFormatOptions);
+                    final boolean isMovedGroup = isMovedGroup(currentInfo.mFlags,
+                            header.mFormatOptions);
+                    final boolean isDeletedGroup = isDeletedGroup(currentInfo.mFlags,
+                            header.mFormatOptions);
                     if (isMovedGroup) continue;
                     boolean same = true;
                     for (int p = 0, j = word.offsetByCodePoints(0, wordPos);
@@ -490,8 +488,8 @@
      */
     static int writeNode(final OutputStream destination, final CharGroupInfo[] infos)
             throws IOException {
-        int size = BinaryDictInputOutput.getGroupCountSize(infos.length);
-        switch (BinaryDictInputOutput.getGroupCountSize(infos.length)) {
+        int size = getGroupCountSize(infos.length);
+        switch (getGroupCountSize(infos.length)) {
             case 1:
                 destination.write((byte)infos.length);
                 break;
@@ -566,4 +564,52 @@
             return null;
         }
     }
+
+    /**
+     * Helper method to hide the actual value of the no children address.
+     */
+    public static boolean hasChildrenAddress(final int address) {
+        return FormatSpec.NO_CHILDREN_ADDRESS != address;
+    }
+
+    /**
+     * Helper method to check whether the group is moved.
+     */
+    public static boolean isMovedGroup(final int flags, final FormatOptions options) {
+        return options.mSupportsDynamicUpdate
+                && ((flags & FormatSpec.MASK_GROUP_ADDRESS_TYPE) == FormatSpec.FLAG_IS_MOVED);
+    }
+
+    /**
+     * Helper method to check whether the dictionary can be updated dynamically.
+     */
+    public static boolean supportsDynamicUpdate(final FormatOptions options) {
+        return options.mVersion >= FormatSpec.FIRST_VERSION_WITH_DYNAMIC_UPDATE
+                && options.mSupportsDynamicUpdate;
+    }
+
+    /**
+     * Helper method to check whether the group is deleted.
+     */
+    public static boolean isDeletedGroup(final int flags, final FormatOptions formatOptions) {
+        return formatOptions.mSupportsDynamicUpdate
+                && ((flags & FormatSpec.MASK_GROUP_ADDRESS_TYPE) == FormatSpec.FLAG_IS_DELETED);
+    }
+
+    /**
+     * Compute the binary size of the group count
+     * @param count the group count
+     * @return the size of the group count, either 1 or 2 bytes.
+     */
+    public static int getGroupCountSize(final int count) {
+        if (FormatSpec.MAX_CHARGROUPS_FOR_ONE_BYTE_CHARGROUP_COUNT >= count) {
+            return 1;
+        } else if (FormatSpec.MAX_CHARGROUPS_IN_A_NODE >= count) {
+            return 2;
+        } else {
+            throw new RuntimeException("Can't have more than "
+                    + FormatSpec.MAX_CHARGROUPS_IN_A_NODE + " groups in a node (found " + count
+                    + ")");
+        }
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java
index 5710e14..a33cddb 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java
@@ -23,6 +23,7 @@
 import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
 import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
+import com.android.inputmethod.latin.utils.JniUtils;
 
 import java.io.ByteArrayOutputStream;
 import java.io.File;
@@ -48,6 +49,13 @@
 
     private static final boolean DBG = MakedictLog.DBG;
 
+    static {
+        JniUtils.loadNativeLibrary();
+    }
+
+    // TODO: implement something sensical instead of just a phony method
+    private static native int doNothing();
+
     // Arbitrary limit to how much passes we consider address size compression should
     // terminate in. At the time of this writing, our largest dictionary completes
     // compression in five passes.
@@ -307,29 +315,12 @@
     }
 
     /**
-     * Compute the binary size of the group count
-     * @param count the group count
-     * @return the size of the group count, either 1 or 2 bytes.
-     */
-    public static int getGroupCountSize(final int count) {
-        if (FormatSpec.MAX_CHARGROUPS_FOR_ONE_BYTE_CHARGROUP_COUNT >= count) {
-            return 1;
-        } else if (FormatSpec.MAX_CHARGROUPS_IN_A_NODE >= count) {
-            return 2;
-        } else {
-            throw new RuntimeException("Can't have more than "
-                    + FormatSpec.MAX_CHARGROUPS_IN_A_NODE + " groups in a node (found " + count
-                    + ")");
-        }
-    }
-
-    /**
      * Compute the binary size of the group count for a node
      * @param node the node
      * @return the size of the group count, either 1 or 2 bytes.
      */
     private static int getGroupCountSize(final Node node) {
-        return getGroupCountSize(node.mData.size());
+        return BinaryDictIOUtils.getGroupCountSize(node.mData.size());
     }
 
     /**
@@ -404,44 +395,13 @@
     }
 
     /**
-     * Helper method to hide the actual value of the no children address.
-     */
-    public static boolean hasChildrenAddress(final int address) {
-        return FormatSpec.NO_CHILDREN_ADDRESS != address;
-    }
-
-    /**
-     * Helper method to check whether the group is moved.
-     */
-    public static boolean isMovedGroup(final int flags, final FormatOptions options) {
-        return options.mSupportsDynamicUpdate
-                && ((flags & FormatSpec.MASK_GROUP_ADDRESS_TYPE) == FormatSpec.FLAG_IS_MOVED);
-    }
-
-    /**
-     * Helper method to check whether the group is deleted.
-     */
-    public static boolean isDeletedGroup(final int flags, final FormatOptions formatOptions) {
-        return formatOptions.mSupportsDynamicUpdate
-                && ((flags & FormatSpec.MASK_GROUP_ADDRESS_TYPE) == FormatSpec.FLAG_IS_DELETED);
-    }
-
-    /**
-     * Helper method to check whether the dictionary can be updated dynamically.
-     */
-    public static boolean supportsDynamicUpdate(final FormatOptions options) {
-        return options.mVersion >= FormatSpec.FIRST_VERSION_WITH_DYNAMIC_UPDATE
-                && options.mSupportsDynamicUpdate;
-    }
-
-    /**
      * Compute the size of the header (flag + [parent address] + characters size) of a CharGroup.
      *
      * @param group the group of which to compute the size of the header
      * @param options file format options.
      */
     private static int getGroupHeaderSize(final CharGroup group, final FormatOptions options) {
-        if (supportsDynamicUpdate(options)) {
+        if (BinaryDictIOUtils.supportsDynamicUpdate(options)) {
             return FormatSpec.GROUP_FLAGS_SIZE + FormatSpec.PARENT_ADDRESS_SIZE
                     + getGroupCharactersSize(group);
         } else {
@@ -461,7 +421,7 @@
      */
     static int getByteSize(final int address) {
         assert(address <= FormatSpec.UINT24_MAX);
-        if (!hasChildrenAddress(address)) {
+        if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
             return 0;
         } else if (Math.abs(address) <= FormatSpec.UINT8_MAX) {
             return 1;
@@ -802,7 +762,7 @@
      */
     private static int writeVariableSignedAddress(final byte[] buffer, int index,
             final int address) {
-        if (!hasChildrenAddress(address)) {
+        if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
             buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
         } else {
             final int absAddress = Math.abs(address);
@@ -966,7 +926,7 @@
 
     private static final int writeParentAddress(final byte[] buffer, final int index,
             final int address, final FormatOptions formatOptions) {
-        if (supportsDynamicUpdate(formatOptions)) {
+        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
             if (address == FormatSpec.NO_PARENT_ADDRESS) {
                 buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
             } else {
@@ -1315,7 +1275,7 @@
 
     static int readParentAddress(final FusionDictionaryBufferInterface buffer,
             final FormatOptions formatOptions) {
-        if (supportsDynamicUpdate(formatOptions)) {
+        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
             final int parentAddress = buffer.readUnsignedInt24();
             final int sign = ((parentAddress & FormatSpec.MSB24) != 0) ? -1 : 1;
             return sign * (parentAddress & FormatSpec.SINT24_MAX);
@@ -1332,7 +1292,7 @@
         ++addressPointer;
 
         final int parentAddress = readParentAddress(buffer, options);
-        if (supportsDynamicUpdate(options)) {
+        if (BinaryDictIOUtils.supportsDynamicUpdate(options)) {
             addressPointer += 3;
         }
 
@@ -1459,7 +1419,7 @@
         final int originalPointer = buffer.position();
         buffer.position(address);
 
-        if (supportsDynamicUpdate(formatOptions)) {
+        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
             result = getWordAtAddressWithParentAddress(buffer, headerSize, address, formatOptions);
         } else {
             result = getWordAtAddressWithoutParentAddress(buffer, headerSize, address,
@@ -1488,13 +1448,13 @@
             do {
                 buffer.position(currentAddress + headerSize);
                 currentInfo = readCharGroup(buffer, currentAddress, options);
-                if (isMovedGroup(currentInfo.mFlags, options)) {
+                if (BinaryDictIOUtils.isMovedGroup(currentInfo.mFlags, options)) {
                     currentAddress = currentInfo.mParentAddress + currentInfo.mOriginalAddress;
                 }
                 if (DBG && loopCounter++ > MAX_JUMPS) {
                     MakedictLog.d("Too many jumps - probably a bug");
                 }
-            } while (isMovedGroup(currentInfo.mFlags, options));
+            } while (BinaryDictIOUtils.isMovedGroup(currentInfo.mFlags, options));
             if (Integer.MIN_VALUE == frequency) frequency = currentInfo.mFrequency;
             for (int i = 0; i < currentInfo.mCharacters.length; ++i) {
                 sGetWordBuffer[index--] =
@@ -1514,7 +1474,7 @@
             final FormatOptions options) {
         buffer.position(headerSize);
         final int count = readCharGroupCount(buffer);
-        int groupOffset = getGroupCountSize(count);
+        int groupOffset = BinaryDictIOUtils.getGroupCountSize(count);
         final StringBuilder builder = new StringBuilder();
         WeightedString result = null;
 
@@ -1527,23 +1487,23 @@
                 result = new WeightedString(builder.toString(), info.mFrequency);
                 break; // and return
             }
-            if (hasChildrenAddress(info.mChildrenAddress)) {
+            if (BinaryDictIOUtils.hasChildrenAddress(info.mChildrenAddress)) {
                 if (info.mChildrenAddress > address) {
                     if (null == last) continue;
                     builder.append(new String(last.mCharacters, 0, last.mCharacters.length));
                     buffer.position(last.mChildrenAddress + headerSize);
                     i = readCharGroupCount(buffer);
-                    groupOffset = last.mChildrenAddress + getGroupCountSize(i);
+                    groupOffset = last.mChildrenAddress + BinaryDictIOUtils.getGroupCountSize(i);
                     last = null;
                     continue;
                 }
                 last = info;
             }
-            if (0 == i && hasChildrenAddress(last.mChildrenAddress)) {
+            if (0 == i && BinaryDictIOUtils.hasChildrenAddress(last.mChildrenAddress)) {
                 builder.append(new String(last.mCharacters, 0, last.mCharacters.length));
                 buffer.position(last.mChildrenAddress + headerSize);
                 i = readCharGroupCount(buffer);
-                groupOffset = last.mChildrenAddress + getGroupCountSize(i);
+                groupOffset = last.mChildrenAddress + BinaryDictIOUtils.getGroupCountSize(i);
                 last = null;
                 continue;
             }
@@ -1576,10 +1536,10 @@
         do { // Scan the linked-list node.
             final int nodeHeadPosition = buffer.position() - headerSize;
             final int count = readCharGroupCount(buffer);
-            int groupOffset = nodeHeadPosition + getGroupCountSize(count);
+            int groupOffset = nodeHeadPosition + BinaryDictIOUtils.getGroupCountSize(count);
             for (int i = count; i > 0; --i) { // Scan the array of CharGroup.
                 CharGroupInfo info = readCharGroup(buffer, groupOffset, options);
-                if (isMovedGroup(info.mFlags, options)) continue;
+                if (BinaryDictIOUtils.isMovedGroup(info.mFlags, options)) continue;
                 ArrayList<WeightedString> shortcutTargets = info.mShortcutTargets;
                 ArrayList<WeightedString> bigrams = null;
                 if (null != info.mBigrams) {
@@ -1592,7 +1552,7 @@
                         bigrams.add(new WeightedString(word.mWord, reconstructedFrequency));
                     }
                 }
-                if (hasChildrenAddress(info.mChildrenAddress)) {
+                if (BinaryDictIOUtils.hasChildrenAddress(info.mChildrenAddress)) {
                     Node children = reverseNodeMap.get(info.mChildrenAddress);
                     if (null == children) {
                         final int currentPosition = buffer.position();
diff --git a/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
index fd728f1..5b10912 100644
--- a/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
@@ -85,7 +85,7 @@
             throw new RuntimeException("this file format does not support parent addresses");
         }
         final int flags = buffer.readUnsignedByte();
-        if (BinaryDictInputOutput.isMovedGroup(flags, formatOptions)) {
+        if (BinaryDictIOUtils.isMovedGroup(flags, formatOptions)) {
             // if the group is moved, the parent address is stored in the destination group.
             // We are guaranteed to process the destination group later, so there is no need to
             // update anything here.
@@ -286,7 +286,7 @@
                 address = buffer.position();
                 final CharGroupInfo currentInfo = BinaryDictInputOutput.readCharGroup(buffer,
                         buffer.position(), header.mFormatOptions);
-                final boolean isMovedGroup = BinaryDictInputOutput.isMovedGroup(currentInfo.mFlags,
+                final boolean isMovedGroup = BinaryDictIOUtils.isMovedGroup(currentInfo.mFlags,
                         header.mFormatOptions);
                 if (isMovedGroup) continue;
                 nodeParentAddress = (currentInfo.mParentAddress == FormatSpec.NO_PARENT_ADDRESS)
diff --git a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryBigramList.java b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryBigramList.java
index f21db25..9f289e9 100644
--- a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryBigramList.java
+++ b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryBigramList.java
@@ -53,7 +53,7 @@
      * Called when loaded from the SQL DB.
      */
     public void addBigram(String word1, String word2, byte fcValue) {
-        if (UserHistoryPredictionDictionary.DBG_SAVE_RESTORE) {
+        if (DynamicPredictionDictionaryBase.DBG_SAVE_RESTORE) {
             Log.d(TAG, "--- add bigram: " + word1 + ", " + word2 + ", " + fcValue);
         }
         final HashMap<String, Byte> map;
@@ -73,7 +73,7 @@
      * Called when inserted to the SQL DB.
      */
     public void updateBigram(String word1, String word2, byte fcValue) {
-        if (UserHistoryPredictionDictionary.DBG_SAVE_RESTORE) {
+        if (DynamicPredictionDictionaryBase.DBG_SAVE_RESTORE) {
             Log.d(TAG, "--- update bigram: " + word1 + ", " + word2 + ", " + fcValue);
         }
         final HashMap<String, Byte> map;
diff --git a/native/jni/Android.mk b/native/jni/Android.mk
index 6e1d765..8d51a2f 100644
--- a/native/jni/Android.mk
+++ b/native/jni/Android.mk
@@ -43,6 +43,7 @@
     com_android_inputmethod_keyboard_ProximityInfo.cpp \
     com_android_inputmethod_latin_BinaryDictionary.cpp \
     com_android_inputmethod_latin_DicTraverseSession.cpp \
+    com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp \
     jni_common.cpp
 
 LATIN_IME_CORE_SRC_FILES := \
diff --git a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
index a25cef5..86c2394 100644
--- a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
+++ b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
@@ -18,37 +18,20 @@
 
 #include "com_android_inputmethod_latin_BinaryDictionary.h"
 
-#include <cerrno>
 #include <cstring> // for memset()
-#include <fcntl.h>
-#include <sys/mman.h>
-#include <unistd.h>
 
 #include "defines.h"
 #include "jni.h"
 #include "jni_common.h"
-#include "suggest/core/dictionary/binary_dictionary_info.h"
 #include "suggest/core/dictionary/dictionary.h"
 #include "suggest/core/suggest_options.h"
-#include "suggest/policyimpl/dictionary/utils/format_utils.h"
+#include "suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.h"
 #include "utils/autocorrection_threshold_utils.h"
 
 namespace latinime {
 
 class ProximityInfo;
 
-// Helper method
-static void releaseDictBuf(const void *dictBuf, const size_t length, const int fd) {
-    int ret = munmap(const_cast<void *>(dictBuf), length);
-    if (ret != 0) {
-        AKLOGE("DICT: Failure in munmap. ret=%d errno=%d", ret, errno);
-    }
-    ret = close(fd);
-    if (ret != 0) {
-        AKLOGE("DICT: Failure in close. ret=%d errno=%d", ret, errno);
-    }
-}
-
 static jlong latinime_BinaryDictionary_open(JNIEnv *env, jclass clazz, jstring sourceDir,
         jlong dictOffset, jlong dictSize, jboolean isUpdatable) {
     PROF_OPEN;
@@ -61,41 +44,16 @@
     char sourceDirChars[sourceDirUtf8Length + 1];
     env->GetStringUTFRegion(sourceDir, 0, env->GetStringLength(sourceDir), sourceDirChars);
     sourceDirChars[sourceDirUtf8Length] = '\0';
-    int fd = 0;
-    void *dictBuf = 0;
-    int offset = 0;
-    const bool updatableMmap = (isUpdatable == JNI_TRUE);
-    const int openMode = updatableMmap ? O_RDWR : O_RDONLY;
-    fd = open(sourceDirChars, openMode);
-    if (fd < 0) {
-        AKLOGE("DICT: Can't open sourceDir. sourceDirChars=%s errno=%d", sourceDirChars, errno);
+    DictionaryStructureWithBufferPolicy *const dictionaryStructureWithBufferPolicy =
+            DictionaryStructureWithBufferPolicyFactory::newDictionaryStructureWithBufferPolicy(
+                    sourceDirChars, static_cast<int>(sourceDirUtf8Length),
+                    static_cast<int>(dictOffset), static_cast<int>(dictSize),
+                    isUpdatable == JNI_TRUE);
+    if (!dictionaryStructureWithBufferPolicy) {
         return 0;
     }
-    int pagesize = getpagesize();
-    offset = static_cast<int>(dictOffset) % pagesize;
-    int adjDictOffset = static_cast<int>(dictOffset) - offset;
-    int adjDictSize = static_cast<int>(dictSize) + offset;
-    const int protMode = updatableMmap ? PROT_READ | PROT_WRITE : PROT_READ;
-    dictBuf = mmap(0, adjDictSize, protMode, MAP_PRIVATE, fd, adjDictOffset);
-    if (dictBuf == MAP_FAILED) {
-        AKLOGE("DICT: Can't mmap dictionary. errno=%d", errno);
-        return 0;
-    }
-    dictBuf = static_cast<char *>(dictBuf) + offset;
-    if (!dictBuf) {
-        AKLOGE("DICT: dictBuf is null");
-        return 0;
-    }
-    Dictionary *dictionary = 0;
-    if (FormatUtils::UNKNOWN_VERSION
-            == FormatUtils::detectFormatVersion(static_cast<uint8_t *>(dictBuf),
-                    static_cast<int>(dictSize))) {
-        AKLOGE("DICT: dictionary format is unknown, bad magic number");
-        releaseDictBuf(static_cast<const char *>(dictBuf) - offset, adjDictSize, fd);
-    } else {
-        dictionary = new Dictionary(env, dictBuf, static_cast<int>(dictSize), fd, offset,
-                updatableMmap);
-    }
+
+    Dictionary *const dictionary = new Dictionary(env, dictionaryStructureWithBufferPolicy);
     PROF_END(66);
     PROF_CLOSE;
     return reinterpret_cast<jlong>(dictionary);
@@ -104,13 +62,6 @@
 static void latinime_BinaryDictionary_close(JNIEnv *env, jclass clazz, jlong dict) {
     Dictionary *dictionary = reinterpret_cast<Dictionary *>(dict);
     if (!dictionary) return;
-    const BinaryDictionaryInfo *const binaryDictionaryInfo = dictionary->getBinaryDictionaryInfo();
-    const int dictBufOffset = binaryDictionaryInfo->getDictBufOffset();
-    const void *dictBuf = binaryDictionaryInfo->getDictBuf();
-    if (!dictBuf) return;
-    releaseDictBuf(static_cast<const char *>(dictBuf) - dictBufOffset,
-            binaryDictionaryInfo->getDictSize() + dictBufOffset,
-            binaryDictionaryInfo->getMmapFd());
     delete dictionary;
 }
 
diff --git a/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp b/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp
new file mode 100644
index 0000000..f78883c
--- /dev/null
+++ b/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "LatinIME: jni: BinaryDictInputOutput"
+
+#include "com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h"
+
+#include "defines.h"
+#include "jni.h"
+#include "jni_common.h"
+
+namespace latinime {
+static int latinime_BinaryDictInputOutput_doNothing(JNIEnv *env, jclass clazz) {
+    // This is a phony method for test - it does nothing. It just returns some value
+    // unlikely to be in memory by chance for testing purposes.
+    // TODO: remove this method.
+    return 2097;
+}
+
+static const JNINativeMethod sMethods[] = {
+    {
+        // TODO: remove this entry when we have one useful method in here
+        const_cast<char *>("doNothing"),
+        const_cast<char *>("()I"),
+        reinterpret_cast<void *>(latinime_BinaryDictInputOutput_doNothing)
+    },
+};
+
+int register_BinaryDictInputOutput(JNIEnv *env) {
+    const char *const kClassPathName =
+            "com/android/inputmethod/latin/makedict/BinaryDictInputOutput";
+    return registerNativeMethods(env, kClassPathName, sMethods, NELEMS(sMethods));
+}
+} // namespace latinime
diff --git a/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h b/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h
new file mode 100644
index 0000000..e622ed4
--- /dev/null
+++ b/native/jni/com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTINPUTOUTPUT_H
+#define _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTINPUTOUTPUT_H
+
+#include "jni.h"
+
+namespace latinime {
+int register_BinaryDictInputOutput(JNIEnv *env);
+} // namespace latinime
+#endif // _COM_ANDROID_INPUTMETHOD_LATIN_MAKEDICT_BINARYDICTINPUTOUTPUT_H
diff --git a/native/jni/jni_common.cpp b/native/jni/jni_common.cpp
index f2867d7..733e15f 100644
--- a/native/jni/jni_common.cpp
+++ b/native/jni/jni_common.cpp
@@ -18,9 +18,12 @@
 
 #include "jni_common.h"
 
+#ifndef HOST_TOOL
 #include "com_android_inputmethod_keyboard_ProximityInfo.h"
 #include "com_android_inputmethod_latin_BinaryDictionary.h"
 #include "com_android_inputmethod_latin_DicTraverseSession.h"
+#endif
+#include "com_android_inputmethod_latin_makedict_BinaryDictInputOutput.h"
 #include "defines.h"
 
 /*
@@ -38,6 +41,7 @@
         AKLOGE("ERROR: JNIEnv is invalid");
         return -1;
     }
+#ifndef HOST_TOOL
     if (!latinime::register_BinaryDictionary(env)) {
         AKLOGE("ERROR: BinaryDictionary native registration failed");
         return -1;
@@ -50,6 +54,11 @@
         AKLOGE("ERROR: ProximityInfo native registration failed");
         return -1;
     }
+#endif
+    if (!latinime::register_BinaryDictInputOutput(env)) {
+        AKLOGE("ERROR: BinaryDictInputOutput native registration failed");
+        return -1;
+    }
     /* success -- return valid version number */
     return JNI_VERSION_1_6;
 }
diff --git a/native/jni/src/suggest/core/dictionary/binary_dictionary_info.h b/native/jni/src/suggest/core/dictionary/binary_dictionary_info.h
deleted file mode 100644
index e50baae..0000000
--- a/native/jni/src/suggest/core/dictionary/binary_dictionary_info.h
+++ /dev/null
@@ -1,67 +0,0 @@
-/*
- * Copyright (C) 2013, The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef LATINIME_BINARY_DICTIONARY_INFO_H
-#define LATINIME_BINARY_DICTIONARY_INFO_H
-
-#include <stdint.h>
-
-#include "defines.h"
-
-namespace latinime {
-
-class BinaryDictionaryInfo {
- public:
-     AK_FORCE_INLINE BinaryDictionaryInfo(const uint8_t *const dictBuf,
-            const int dictSize, const int mmapFd, const int dictBufOffset, const bool isUpdatable)
-            : mDictBuf(dictBuf), mDictSize(dictSize), mMmapFd(mmapFd),
-              mDictBufOffset(dictBufOffset), mIsUpdatable(isUpdatable) {}
-
-    ~BinaryDictionaryInfo() {}
-
-    AK_FORCE_INLINE const uint8_t *getDictBuf() const {
-        return mDictBuf;
-    }
-
-    AK_FORCE_INLINE int getDictSize() const {
-        return mDictSize;
-    }
-
-    AK_FORCE_INLINE int getMmapFd() const {
-        return mMmapFd;
-    }
-
-    AK_FORCE_INLINE int getDictBufOffset() const {
-        return mDictBufOffset;
-    }
-
-    AK_FORCE_INLINE bool isDynamicallyUpdatable() const {
-        // TODO: Support dynamic dictionary formats.
-        const bool isUpdatableDictionaryFormat = false;
-        return mIsUpdatable && isUpdatableDictionaryFormat;
-    }
-
- private:
-    DISALLOW_COPY_AND_ASSIGN(BinaryDictionaryInfo);
-
-    const uint8_t *const mDictBuf;
-    const int mDictSize;
-    const int mMmapFd;
-    const int mDictBufOffset;
-    const bool mIsUpdatable;
-};
-}
-#endif /* LATINIME_BINARY_DICTIONARY_INFO_H */
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.cpp b/native/jni/src/suggest/core/dictionary/dictionary.cpp
index af00e99..8418a60 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.cpp
+++ b/native/jni/src/suggest/core/dictionary/dictionary.cpp
@@ -23,23 +23,19 @@
 #include "defines.h"
 #include "suggest/core/dictionary/bigram_dictionary.h"
 #include "suggest/core/policy/dictionary_header_structure_policy.h"
+#include "suggest/core/policy/dictionary_structure_with_buffer_policy.h"
 #include "suggest/core/session/dic_traverse_session.h"
 #include "suggest/core/suggest.h"
 #include "suggest/core/suggest_options.h"
-#include "suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.h"
 #include "suggest/policyimpl/gesture/gesture_suggest_policy_factory.h"
 #include "suggest/policyimpl/typing/typing_suggest_policy_factory.h"
 #include "utils/log_utils.h"
 
 namespace latinime {
 
-Dictionary::Dictionary(JNIEnv *env, void *dict, int dictSize, int mmapFd,
-        int dictBufOffset, bool isUpdatable)
-        : mBinaryDictionaryInfo(static_cast<const uint8_t *>(dict), dictSize, mmapFd,
-                dictBufOffset, isUpdatable),
-          mDictionaryStructureWithBufferPolicy(DictionaryStructureWithBufferPolicyFactory
-                  ::newDictionaryStructureWithBufferPolicy(
-                          static_cast<const uint8_t *>(dict), dictSize)),
+Dictionary::Dictionary(JNIEnv *env,
+        DictionaryStructureWithBufferPolicy *const dictionaryStructureWithBufferPolicy)
+        : mDictionaryStructureWithBufferPolicy(dictionaryStructureWithBufferPolicy),
           mBigramDictionary(new BigramDictionary(mDictionaryStructureWithBufferPolicy)),
           mGestureSuggest(new Suggest(GestureSuggestPolicyFactory::getGestureSuggestPolicy())),
           mTypingSuggest(new Suggest(TypingSuggestPolicyFactory::getTypingSuggestPolicy())) {
@@ -102,32 +98,18 @@
 }
 
 void Dictionary::addUnigramWord(const int *const word, const int length, const int probability) {
-    if (!mBinaryDictionaryInfo.isDynamicallyUpdatable()) {
-        // This method should not be called for non-updatable dictionary.
-        AKLOGI("Warning: Dictionary::addUnigramWord() is called for non-updatable dictionary.");
-        return;
-    }
-    // TODO: Support dynamic update
+    mDictionaryStructureWithBufferPolicy->addUnigramWord(word, length, probability);
 }
 
 void Dictionary::addBigramWords(const int *const word0, const int length0, const int *const word1,
         const int length1, const int probability) {
-    if (!mBinaryDictionaryInfo.isDynamicallyUpdatable()) {
-        // This method should not be called for non-updatable dictionary.
-        AKLOGI("Warning: Dictionary::addBigramWords() is called for non-updatable dictionary.");
-        return;
-    }
-    // TODO: Support dynamic update
+    mDictionaryStructureWithBufferPolicy->addBigramWords(word0, length0, word1, length1,
+            probability);
 }
 
 void Dictionary::removeBigramWords(const int *const word0, const int length0,
         const int *const word1, const int length1) {
-    if (!mBinaryDictionaryInfo.isDynamicallyUpdatable()) {
-        // This method should not be called for non-updatable dictionary.
-        AKLOGI("Warning: Dictionary::removeBigramWords() is called for non-updatable dictionary.");
-        return;
-    }
-    // TODO: Support dynamic update
+    mDictionaryStructureWithBufferPolicy->removeBigramWords(word0, length0, word1, length1);
 }
 
 void Dictionary::logDictionaryInfo(JNIEnv *const env) const {
@@ -154,9 +136,8 @@
             dateStringCharBuffer, BUFFER_SIZE);
 
     LogUtils::logToJava(env,
-            "Dictionary info: dictionary = %s ; version = %s ; date = %s ; filesize = %i",
-            dictionaryIdCharBuffer, versionStringCharBuffer, dateStringCharBuffer,
-            mBinaryDictionaryInfo.getDictSize());
+            "Dictionary info: dictionary = %s ; version = %s ; date = %s",
+            dictionaryIdCharBuffer, versionStringCharBuffer, dateStringCharBuffer);
 }
 
 } // namespace latinime
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.h b/native/jni/src/suggest/core/dictionary/dictionary.h
index 17ce479..0afe5a5 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.h
+++ b/native/jni/src/suggest/core/dictionary/dictionary.h
@@ -21,7 +21,6 @@
 
 #include "defines.h"
 #include "jni.h"
-#include "suggest/core/dictionary/binary_dictionary_info.h"
 
 namespace latinime {
 
@@ -54,8 +53,8 @@
     static const int KIND_FLAG_POSSIBLY_OFFENSIVE = 0x80000000;
     static const int KIND_FLAG_EXACT_MATCH = 0x40000000;
 
-    Dictionary(JNIEnv *env, void *dict, int dictSize, int mmapFd, int dictBufOffset,
-            bool isUpdatable);
+    Dictionary(JNIEnv *env,
+            DictionaryStructureWithBufferPolicy *const dictionaryStructureWithBufferPoilcy);
 
     int getSuggestions(ProximityInfo *proximityInfo, DicTraverseSession *traverseSession,
             int *xcoordinates, int *ycoordinates, int *times, int *pointerIds, int *inputCodePoints,
@@ -78,11 +77,6 @@
     void removeBigramWords(const int *const word0, const int length0, const int *const word1,
             const int length1);
 
-    // TODO: Remove.
-    const BinaryDictionaryInfo *getBinaryDictionaryInfo() const {
-        return &mBinaryDictionaryInfo;
-    }
-
     const DictionaryStructureWithBufferPolicy *getDictionaryStructurePolicy() const {
         return mDictionaryStructureWithBufferPolicy;
     }
@@ -92,11 +86,10 @@
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Dictionary);
 
-    const BinaryDictionaryInfo mBinaryDictionaryInfo;
     DictionaryStructureWithBufferPolicy *const mDictionaryStructureWithBufferPolicy;
-    const BigramDictionary *mBigramDictionary;
-    SuggestInterface *mGestureSuggest;
-    SuggestInterface *mTypingSuggest;
+    const BigramDictionary *const mBigramDictionary;
+    const SuggestInterface *const mGestureSuggest;
+    const SuggestInterface *const mTypingSuggest;
 
     void logDictionaryInfo(JNIEnv *const env) const;
 };
diff --git a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
index 37daef9..5324115 100644
--- a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
+++ b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
@@ -59,6 +59,18 @@
 
     virtual const DictionaryShortcutsStructurePolicy *getShortcutsStructurePolicy() const = 0;
 
+    // Returns whether the update was success or not.
+    virtual bool addUnigramWord(const int *const word, const int length,
+            const int probability) = 0;
+
+    // Returns whether the update was success or not.
+    virtual bool addBigramWords(const int *const word0, const int length0, const int *const word1,
+            const int length1, const int probability) = 0;
+
+    // Returns whether the update was success or not.
+    virtual bool removeBigramWords(const int *const word0, const int length0,
+            const int *const word1, const int length1) = 0;
+
  protected:
     DictionaryStructureWithBufferPolicy() {}
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.cpp b/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.cpp
index 34f092f..cc5252c 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.cpp
@@ -22,18 +22,29 @@
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h"
 #include "suggest/policyimpl/dictionary/patricia_trie_policy.h"
 #include "suggest/policyimpl/dictionary/utils/format_utils.h"
+#include "suggest/policyimpl/dictionary/utils/mmaped_buffer.h"
 
 namespace latinime {
 
 /* static */ DictionaryStructureWithBufferPolicy *DictionaryStructureWithBufferPolicyFactory
-        ::newDictionaryStructureWithBufferPolicy(const uint8_t *const dictBuf,
-                const int dictSize) {
-    switch (FormatUtils::detectFormatVersion(dictBuf, dictSize)) {
+        ::newDictionaryStructureWithBufferPolicy(const char *const path, const int pathLength,
+                const int bufOffset, const int size, const bool isUpdatable) {
+    // Allocated buffer in MmapedBuffer::openBuffer() will be freed in the destructor of
+    // impl classes of DictionaryStructureWithBufferPolicy.
+    const MmapedBuffer *const mmapedBuffer = MmapedBuffer::openBuffer(path, pathLength, bufOffset,
+            size, isUpdatable);
+    if (!mmapedBuffer) {
+        return 0;
+    }
+    switch (FormatUtils::detectFormatVersion(mmapedBuffer->getBuffer(),
+            mmapedBuffer->getBufferSize())) {
         case FormatUtils::VERSION_2:
-            return new PatriciaTriePolicy(dictBuf);
+            return new PatriciaTriePolicy(mmapedBuffer);
         case FormatUtils::VERSION_3:
-            return new DynamicPatriciaTriePolicy(dictBuf);
+            return new DynamicPatriciaTriePolicy(mmapedBuffer);
         default:
+            AKLOGE("DICT: dictionary format is unknown, bad magic number");
+            delete mmapedBuffer;
             ASSERT(false);
             return 0;
     }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.h b/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.h
index 53eb8f9..1cb7a89 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dictionary_structure_with_buffer_policy_factory.h
@@ -27,7 +27,8 @@
 class DictionaryStructureWithBufferPolicyFactory {
  public:
     static DictionaryStructureWithBufferPolicy *newDictionaryStructureWithBufferPolicy(
-            const uint8_t *const dictBuf, const int dictSize);
+            const char *const path, const int pathLength, const int bufOffset, const int size,
+            const bool isUpdatable);
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DictionaryStructureWithBufferPolicyFactory);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
index cca8010..3000860 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
@@ -231,4 +231,34 @@
     return nodeReader.getBigramsPos();
 }
 
+bool DynamicPatriciaTriePolicy::addUnigramWord(const int *const word, const int length,
+        const int probability) {
+    if (!mBuffer->isUpdatable()) {
+        AKLOGI("Warning: addUnigramWord() is called for non-updatable dictionary.");
+        return false;
+    }
+    // TODO: Implement.
+    return false;
+}
+
+bool DynamicPatriciaTriePolicy::addBigramWords(const int *const word0, const int length0,
+        const int *const word1, const int length1, const int probability) {
+    if (!mBuffer->isUpdatable()) {
+        AKLOGI("Warning: addBigramWords() is called for non-updatable dictionary.");
+        return false;
+    }
+    // TODO: Implement.
+    return false;
+}
+
+bool DynamicPatriciaTriePolicy::removeBigramWords(const int *const word0, const int length0,
+        const int *const word1, const int length1) {
+    if (!mBuffer->isUpdatable()) {
+        AKLOGI("Warning: removeBigramWords() is called for non-updatable dictionary.");
+        return false;
+    }
+    // TODO: Implement.
+    return false;
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
index ad8911c..708967d 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
@@ -24,6 +24,7 @@
 #include "suggest/policyimpl/dictionary/bigram/bigram_list_policy.h"
 #include "suggest/policyimpl/dictionary/header/header_policy.h"
 #include "suggest/policyimpl/dictionary/shortcut/shortcut_list_policy.h"
+#include "suggest/policyimpl/dictionary/utils/mmaped_buffer.h"
 
 namespace latinime {
 
@@ -32,11 +33,14 @@
 
 class DynamicPatriciaTriePolicy : public DictionaryStructureWithBufferPolicy {
  public:
-    DynamicPatriciaTriePolicy(const uint8_t *const dictBuf)
-            : mHeaderPolicy(dictBuf), mDictRoot(dictBuf + mHeaderPolicy.getSize()),
+    DynamicPatriciaTriePolicy(const MmapedBuffer *const buffer)
+            : mBuffer(buffer), mHeaderPolicy(mBuffer->getBuffer()),
+              mDictRoot(mBuffer->getBuffer() + mHeaderPolicy.getSize()),
               mBigramListPolicy(mDictRoot), mShortcutListPolicy(mDictRoot) {}
 
-    ~DynamicPatriciaTriePolicy() {}
+    ~DynamicPatriciaTriePolicy() {
+        delete mBuffer;
+    }
 
     AK_FORCE_INLINE int getRootPosition() const {
         return 0;
@@ -70,10 +74,19 @@
         return &mShortcutListPolicy;
     }
 
+    bool addUnigramWord(const int *const word, const int length, const int probability);
+
+    bool addBigramWords(const int *const word0, const int length0, const int *const word1,
+            const int length1, const int probability);
+
+    bool removeBigramWords(const int *const word0, const int length0, const int *const word1,
+            const int length1);
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicPatriciaTriePolicy);
     static const int MAX_CHILD_COUNT_TO_AVOID_INFINITE_LOOP;
 
+    const MmapedBuffer *const mBuffer;
     const HeaderPolicy mHeaderPolicy;
     // TODO: Consolidate mDictRoot.
     const uint8_t *const mDictRoot;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/header/header_reading_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/header/header_reading_utils.cpp
index 23b88ec..f323876 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/header/header_reading_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/header/header_reading_utils.cpp
@@ -34,7 +34,7 @@
 const HeaderReadingUtils::DictionaryFlags
         HeaderReadingUtils::NO_FLAGS = 0;
 // Flags for special processing
-// Those *must* match the flags in makedict (BinaryDictInputOutput#*_PROCESSING_FLAG) or
+// Those *must* match the flags in makedict (FormatSpec#*_PROCESSING_FLAG) or
 // something very bad (like, the apocalypse) will happen. Please update both at the same time.
 const HeaderReadingUtils::DictionaryFlags
         HeaderReadingUtils::GERMAN_UMLAUT_PROCESSING_FLAG = 0x1;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
index 2e34480..0d85050 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
@@ -24,6 +24,7 @@
 #include "suggest/policyimpl/dictionary/bigram/bigram_list_policy.h"
 #include "suggest/policyimpl/dictionary/header/header_policy.h"
 #include "suggest/policyimpl/dictionary/shortcut/shortcut_list_policy.h"
+#include "suggest/policyimpl/dictionary/utils/mmaped_buffer.h"
 
 namespace latinime {
 
@@ -32,11 +33,14 @@
 
 class PatriciaTriePolicy : public DictionaryStructureWithBufferPolicy {
  public:
-    PatriciaTriePolicy(const uint8_t *const dictBuf)
-            : mHeaderPolicy(dictBuf), mDictRoot(dictBuf + mHeaderPolicy.getSize()),
+    PatriciaTriePolicy(const MmapedBuffer *const buffer)
+            : mBuffer(buffer), mHeaderPolicy(mBuffer->getBuffer()),
+              mDictRoot(mBuffer->getBuffer() + mHeaderPolicy.getSize()),
               mBigramListPolicy(mDictRoot), mShortcutListPolicy(mDictRoot) {}
 
-    ~PatriciaTriePolicy() {}
+    ~PatriciaTriePolicy() {
+        delete mBuffer;
+    }
 
     AK_FORCE_INLINE int getRootPosition() const {
         return 0;
@@ -70,9 +74,30 @@
         return &mShortcutListPolicy;
     }
 
+    bool addUnigramWord(const int *const word, const int length, const int probability) {
+        // This method should not be called for non-updatable dictionary.
+        AKLOGI("Warning: addUnigramWord() is called for non-updatable dictionary.");
+        return false;
+    }
+
+    bool addBigramWords(const int *const word0, const int length0, const int *const word1,
+            const int length1, const int probability) {
+        // This method should not be called for non-updatable dictionary.
+        AKLOGI("Warning: addBigramWords() is called for non-updatable dictionary.");
+        return false;
+    }
+
+    bool removeBigramWords(const int *const word0, const int length0, const int *const word1,
+            const int length1) {
+        // This method should not be called for non-updatable dictionary.
+        AKLOGI("Warning: removeBigramWords() is called for non-updatable dictionary.");
+        return false;
+    }
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(PatriciaTriePolicy);
 
+    const MmapedBuffer *const mBuffer;
     const HeaderPolicy mHeaderPolicy;
     const uint8_t *const mDictRoot;
     const BigramListPolicy mBigramListPolicy;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/mmaped_buffer.h b/native/jni/src/suggest/policyimpl/dictionary/utils/mmaped_buffer.h
new file mode 100644
index 0000000..e3aabb0
--- /dev/null
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/mmaped_buffer.h
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2013, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LATINIME_MMAPED_BUFFER_H
+#define LATINIME_MMAPED_BUFFER_H
+
+#include <cerrno>
+#include <fcntl.h>
+#include <stdint.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "defines.h"
+
+namespace latinime {
+
+class MmapedBuffer {
+ public:
+    static MmapedBuffer* openBuffer(const char *const path, const int pathLength,
+            const int bufOffset, const int size, const bool isUpdatable) {
+        const int openMode = isUpdatable ? O_RDWR : O_RDONLY;
+        const int fd = open(path, openMode);
+        if (fd < 0) {
+            AKLOGE("DICT: Can't open the source. path=%s errno=%d", path, errno);
+            return 0;
+        }
+        const int pagesize = getpagesize();
+        const int offset = bufOffset % pagesize;
+        int adjOffset = bufOffset - offset;
+        int adjSize = size + offset;
+        const int protMode = isUpdatable ? PROT_READ | PROT_WRITE : PROT_READ;
+        void *const mmapedBuffer = mmap(0, adjSize, protMode, MAP_PRIVATE, fd, adjOffset);
+        if (mmapedBuffer == MAP_FAILED) {
+            AKLOGE("DICT: Can't mmap dictionary. errno=%d", errno);
+            close(fd);
+            return 0;
+        }
+        uint8_t *const buffer = static_cast<uint8_t *>(mmapedBuffer) + bufOffset;
+        if (!buffer) {
+            AKLOGE("DICT: buffer is null");
+            close(fd);
+            return 0;
+        }
+        return new MmapedBuffer(buffer, adjSize, fd, adjOffset, isUpdatable);
+    }
+
+    ~MmapedBuffer() {
+        int ret = munmap(static_cast<void *>(mBuffer - mBufferOffset),
+                mBufferSize + mBufferOffset);
+        if (ret != 0) {
+            AKLOGE("DICT: Failure in munmap. ret=%d errno=%d", ret, errno);
+        }
+        ret = close(mMmapFd);
+        if (ret != 0) {
+            AKLOGE("DICT: Failure in close. ret=%d errno=%d", ret, errno);
+        }
+    }
+
+    AK_FORCE_INLINE uint8_t *getBuffer() const {
+        return mBuffer;
+    }
+
+    AK_FORCE_INLINE int getBufferSize() const {
+        return mBufferSize;
+    }
+
+    AK_FORCE_INLINE bool isUpdatable() const {
+        return mIsUpdatable;
+    }
+
+ private:
+    AK_FORCE_INLINE MmapedBuffer(uint8_t *const buffer, const int bufferSize, const int mmapFd,
+            const int bufferOffset, const bool isUpdatable)
+            : mBuffer(buffer), mBufferSize(bufferSize), mMmapFd(mmapFd),
+              mBufferOffset(bufferOffset), mIsUpdatable(isUpdatable) {}
+
+    DISALLOW_IMPLICIT_CONSTRUCTORS(MmapedBuffer);
+
+    uint8_t *const mBuffer;
+    const int mBufferSize;
+    const int mMmapFd;
+    const int mBufferOffset;
+    const bool mIsUpdatable;
+};
+}
+#endif /* LATINIME_MMAPED_BUFFER_H */
diff --git a/tools/dicttool/Android.mk b/tools/dicttool/Android.mk
index d06be58..f076ef2 100644
--- a/tools/dicttool/Android.mk
+++ b/tools/dicttool/Android.mk
@@ -13,27 +13,34 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-LOCAL_PATH := $(call my-dir)
+LATINIME_DICTTOOL_AOSP_LOCAL_PATH := $(call my-dir)
+LOCAL_PATH := $(LATINIME_DICTTOOL_AOSP_LOCAL_PATH)
+LATINIME_HOST_NATIVE_LIBNAME := liblatinime-aosp-dicttool-host
+include $(LOCAL_PATH)/NativeLib.mk
+
+######################################
+LOCAL_PATH := $(LATINIME_DICTTOOL_AOSP_LOCAL_PATH)
 include $(CLEAR_VARS)
 
-BUILD_TOP := ../../../../..
-LATINIME_DIR := $(BUILD_TOP)/packages/inputmethods/LatinIME
-LATINIME_BASE_SOURCE_DIRECTORY := $(LATINIME_DIR)/java/src/com/android/inputmethod
-LATINIME_CORE_SOURCE_DIRECTORY := $(LATINIME_BASE_SOURCE_DIRECTORY)/latin
+LATINIME_LOCAL_DIR := ../..
+LATINIME_BASE_SOURCE_DIRECTORY := $(LATINIME_LOCAL_DIR)/java/src/com/android/inputmethod
 LATINIME_ANNOTATIONS_SOURCE_DIRECTORY := $(LATINIME_BASE_SOURCE_DIRECTORY)/annotations
+LATINIME_CORE_SOURCE_DIRECTORY := $(LATINIME_BASE_SOURCE_DIRECTORY)/latin
 MAKEDICT_CORE_SOURCE_DIRECTORY := $(LATINIME_CORE_SOURCE_DIRECTORY)/makedict
-DICTTOOL_COMPAT_TESTS_DIRECTORY := compat
-DICTTOOL_ONDEVICE_TESTS_DIRECTORY := \
-        $(LATINIME_DIR)/tests/src/com/android/inputmethod/latin/makedict/
-
 USED_TARGETTED_UTILS := \
         $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/ByteArrayWrapper.java \
-        $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/CollectionUtils.java
+        $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/CollectionUtils.java \
+        $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/JniUtils.java
+
+DICTTOOL_ONDEVICE_TESTS_DIRECTORY := \
+        $(LATINIME_LOCAL_DIR)/tests/src/com/android/inputmethod/latin/makedict/
+DICTTOOL_COMPAT_TESTS_DIRECTORY := compat
 
 LOCAL_MAIN_SRC_FILES := $(call all-java-files-under, $(MAKEDICT_CORE_SOURCE_DIRECTORY))
 LOCAL_TOOL_SRC_FILES := $(call all-java-files-under, src)
 LOCAL_ANNOTATIONS_SRC_FILES := \
         $(call all-java-files-under, $(LATINIME_ANNOTATIONS_SOURCE_DIRECTORY))
+
 LOCAL_SRC_FILES := $(LOCAL_TOOL_SRC_FILES) \
         $(filter-out $(addprefix %/, $(notdir $(LOCAL_TOOL_SRC_FILES))), $(LOCAL_MAIN_SRC_FILES)) \
         $(LOCAL_ANNOTATIONS_SRC_FILES) \
@@ -44,9 +51,13 @@
         $(USED_TARGETTED_UTILS)
 
 LOCAL_JAVA_LIBRARIES := junit
-
+LOCAL_ADDITIONAL_DEPENDENCIES := $(LATINIME_HOST_NATIVE_LIBNAME)
 LOCAL_JAR_MANIFEST := etc/manifest.txt
 LOCAL_MODULE := dicttool_aosp
 
 include $(BUILD_HOST_JAVA_LIBRARY)
 include $(LOCAL_PATH)/etc/Android.mk
+
+# Clear our private variables
+LATINIME_DICTTOOL_AOSP_LOCAL_PATH :=
+LATINIME_LOCAL_DIR :=
diff --git a/tools/dicttool/NativeLib.mk b/tools/dicttool/NativeLib.mk
new file mode 100644
index 0000000..eeae003
--- /dev/null
+++ b/tools/dicttool/NativeLib.mk
@@ -0,0 +1,51 @@
+#
+# Copyright (C) 2013 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+LOCAL_PATH := $(call my-dir)
+include $(CLEAR_VARS)
+
+# Need to define the name of the library in the caller in LATINIME_HOST_NATIVE_LIBNAME
+
+LATINIME_DIR_RELATIVE_TO_DICTTOOL := ../..
+
+ifneq ($(strip $(HOST_JDK_IS_64BIT_VERSION)),)
+LOCAL_CFLAGS += -m64
+LOCAL_LDFLAGS += -m64
+endif #HOST_JDK_IS_64BIT_VERSION
+
+LOCAL_CFLAGS += -DHOST_TOOL -fPIC
+LOCAL_NO_DEFAULT_COMPILER_FLAGS := true
+
+LATINIME_NATIVE_JNI_DIR := $(LATINIME_DIR_RELATIVE_TO_DICTTOOL)/native/jni
+LATINIME_NATIVE_SRC_DIR := $(LATINIME_DIR_RELATIVE_TO_DICTTOOL)/native/jni/src
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/$(LATINIME_NATIVE_SRC_DIR)
+# Used in jni_common.cpp to avoid registering useless methods.
+
+LATIN_IME_JNI_SRC_FILES := \
+    com_android_inputmethod_latin_makedict_BinaryDictInputOutput.cpp \
+    jni_common.cpp
+
+LATIN_IME_CORE_SRC_FILES :=
+
+LOCAL_SRC_FILES := \
+    $(addprefix $(LATINIME_NATIVE_JNI_DIR)/, $(LATIN_IME_JNI_SRC_FILES)) \
+    $(addprefix $(LATINIME_NATIVE_SRC_DIR)/, $(LATIN_IME_CORE_SRC_FILES))
+
+LOCAL_MODULE := $(LATINIME_HOST_NATIVE_LIBNAME)
+
+include $(BUILD_HOST_SHARED_LIBRARY)
+
+# Clear our private variables
+LATINIME_DIR_RELATIVE_TO_DICTTOOL := ../..
diff --git a/tools/dicttool/compat/android/util/Log.java b/tools/dicttool/compat/android/util/Log.java
index d9df3a4..b3b6dd8 100644
--- a/tools/dicttool/compat/android/util/Log.java
+++ b/tools/dicttool/compat/android/util/Log.java
@@ -25,13 +25,13 @@
     public static void d(final String tag, final String message) {
         System.out.println(tag + " : " + message);
     }
-    public static void d(final String tag, final String message, final Exception e) {
+    public static void d(final String tag, final String message, final Throwable e) {
         System.out.println(tag + " : " + message + " : " + e);
     }
     public static void e(final String tag, final String message) {
         d(tag, message);
     }
-    public static void e(final String tag, final String message, final Exception e) {
-        e(tag, message, e);
+    public static void e(final String tag, final String message, final Throwable e) {
+        d(tag, message, e);
     }
 }
diff --git a/tools/dicttool/compat/com/android/inputmethod/latin/define/JniLibName.java b/tools/dicttool/compat/com/android/inputmethod/latin/define/JniLibName.java
new file mode 100644
index 0000000..c68bdaa
--- /dev/null
+++ b/tools/dicttool/compat/com/android/inputmethod/latin/define/JniLibName.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.latin.define;
+
+public final class JniLibName {
+    private JniLibName() {
+        // This class is not publicly instantiable.
+    }
+
+    public static final String JNI_LIB_NAME = "latinime-dicttool-host";
+}
diff --git a/tools/dicttool/etc/dicttool_aosp b/tools/dicttool/etc/dicttool_aosp
index cc7111a..65a1c3a 100755
--- a/tools/dicttool/etc/dicttool_aosp
+++ b/tools/dicttool/etc/dicttool_aosp
@@ -69,4 +69,4 @@
 fi
 
 # might need more memory, e.g. -Xmx128M
-exec java -ea -classpath "$libpath":"$jarpath" "$classname" "$@"
+exec java -ea -classpath "$libpath":"$jarpath" -Djava.library.path="$libdir" "$classname" "$@"